module Macbeth.Wx.BoardState (
  BoardState(..),
  DraggedPiece(..),
  Origin(..),
  PieceMove (..),

  pickUpPieceFromHolding,
  discardDraggedPiece,

  setPromotion,
  togglePromotion,

  pointToSquare,
  movePiece,

  update,
  setResult,
  resize,
  invertPerspective,

  performPreMoves,
  cancelLastPreMove,

  setPieceSet,
  getPieceHolding,

  getSelectedSquare,
  initBoardState
) where

import Macbeth.Fics.Api.Api
import Macbeth.Fics.Api.Move
import Macbeth.Fics.Api.Game
import Macbeth.Wx.PieceSet

import Control.Monad
import Control.Concurrent.STM
import Data.Maybe
import Data.List
import Graphics.UI.WX hiding (position, update, resize, when)
import Safe
import System.IO


data BoardState = BoardState {
    lastMove :: Move
  , gameResult :: Maybe GameResult
  , pieceMove :: [PieceMove]
  , moves :: [Move]
  , _position :: Position
  , preMoves :: [PieceMove]
  , perspective :: PColor
  , mousePt :: Point
  , promotion :: PType
  , draggedPiece :: Maybe DraggedPiece
  , isWaiting :: Bool
  , psize :: Int
  , scale :: Double
  , pieceSet :: PieceSet
  , phW :: [PType]
  , phB :: [PType] }


data DraggedPiece = DraggedPiece Point Piece Origin deriving (Show)

data Origin = FromHolding | FromBoard Square deriving (Show)

data PieceMove = PieceMove { piece :: Piece, from :: Square, to :: Square } | DropMove Piece Square

instance Show PieceMove where
  show (PieceMove _ s1 s2) = show s1 ++ show s2
  show (DropMove (Piece p _) s) = show p ++ "@" ++ show s


pickUpPieceFromHolding :: TVar BoardState -> PType -> IO ()
pickUpPieceFromHolding vState p = atomically $ modifyTVar vState
  (\s -> let color = colorUser (lastMove s)
             isAllowed = isGameUser (lastMove s) && p `elem` getPieceHolding color s
         in if isAllowed
            then s{draggedPiece = Just $ DraggedPiece (mousePt s) (Piece p color) FromHolding }
            else s)


discardDraggedPiece :: TVar BoardState -> IO ()
discardDraggedPiece vState = atomically $ modifyTVar vState (\s -> s {
    draggedPiece = Nothing
  , _position = movePieces (preMoves s) (position $ lastMove s)})


invertPerspective :: TVar BoardState -> IO ()
invertPerspective vState = atomically $ modifyTVar vState (\s -> s{perspective = invert $ perspective s})


setResult :: TVar BoardState -> GameResult -> IO ()
setResult vState r = atomically $ modifyTVar vState (\s -> s{
     gameResult = Just r
   , _position = position $ lastMove s
   , preMoves = []
   , draggedPiece = Nothing})


setPromotion :: PType -> TVar BoardState -> IO ()
setPromotion p vState = atomically $ modifyTVar vState (\s -> s{promotion = p})


togglePromotion :: TVar BoardState -> IO PType
togglePromotion vState = atomically $ do
  modifyTVar vState (\s -> s{promotion = togglePromotion' (promotion s)})
  promotion `fmap` readTVar vState
  where
    togglePromotion' :: PType -> PType
    togglePromotion' p = let px = [Queen, Rook, Knight, Bishop]
                         in px !! ((fromJust (p `elemIndex` px) + 1) `mod` length px)


update :: TVar BoardState -> Move -> MoveModifier -> IO ()
update vBoardState move ctx = atomically $ modifyTVar vBoardState (\s -> s {
    isWaiting = isNextMoveUser move
  , pieceMove = diffPosition (position $ lastMove s) (position move)
  , moves = addtoHistory move ctx (moves s)
  , lastMove = move
  , _position = movePieces (preMoves s) (position move)})


diffPosition :: Position -> Position -> [PieceMove]
diffPosition before after =
  let from = before \\ after
      to = after \\ before
  in [PieceMove piece1 s1 s2 | (s1, piece1) <- from, (s2, piece2) <- to, piece1 == piece2, s1 /= s2 ]


addtoHistory :: Move -> MoveModifier -> [Move] -> [Move]
addtoHistory _ Illegal mx = mx
addtoHistory m (Takeback _) mx = m : tail (dropWhile (not . equal m) mx)
  where
    equal :: Move -> Move -> Bool
    equal m1 m2 = (moveNumber m1 == moveNumber m2) && (turn m1 == turn m2)
addtoHistory m _ mx = m : mx


resize :: Panel () -> TVar BoardState -> IO ()
resize p vState = do
  (Size x _) <- get p size
  let psize' = pieceSetFindSize x
  atomically $ modifyTVar vState (\s -> s { psize = psize', scale = fromIntegral x / 8 / fromIntegral psize'})


cancelLastPreMove :: TVar BoardState -> IO ()
cancelLastPreMove vBoardState = atomically $ modifyTVar vBoardState (\s ->
  let preMoves' = fromMaybe [] $ initMay (preMoves s) in s {
      preMoves = preMoves'
    , _position = movePieces preMoves' (position $ lastMove s)})


performPreMoves :: TVar BoardState -> Handle -> IO ()
performPreMoves vBoardState h = do
  preMoves' <- preMoves `fmap` readTVarIO vBoardState
  unless (null preMoves') $ do
    atomically $ modifyTVar vBoardState (\s -> s {
      isWaiting = False,
      preMoves = tail preMoves'})
    hPutStrLn h $ "6 " ++ show (head preMoves' )


setPieceSet :: TVar BoardState -> PieceSet -> IO ()
setPieceSet vState ps = atomically (modifyTVar vState (\s -> s { pieceSet = ps }))


getPieceHolding :: PColor -> BoardState -> [PType]
getPieceHolding White bs = phW bs
getPieceHolding Black bs = phB bs


getSelectedSquare :: BoardState -> Square
getSelectedSquare state = pointToSquare state (mousePt state)


pointToSquare :: BoardState -> Point -> Square
pointToSquare state (Point x y) = Square
  (intToCol (perspective state) (floor $ fromIntegral x / fieldSize state))
  (intToRow (perspective state) (floor $ fromIntegral y / fieldSize state))
  where
    intToRow :: PColor -> Int -> Row
    intToRow White = toEnum . abs . (7-)
    intToRow Black = toEnum

    intToCol :: PColor -> Int -> Column
    intToCol White = toEnum
    intToCol Black = toEnum . abs . (7-)

    fieldSize :: BoardState -> Double
    fieldSize bs = scale bs * fromIntegral (psize bs)


movePieces :: [PieceMove] -> Position -> Position
movePieces moves pos = foldl (flip movePiece) pos moves


movePiece :: PieceMove -> Position -> Position
movePiece (PieceMove piece from to) position = filter (\(s, _) -> s /= from && s /= to) position ++ [(to, piece)]
movePiece (DropMove piece sq) pos = filter (\(s, _) -> s /= sq) pos ++ [(sq, piece)]


initBoardState :: Move -> BoardState
initBoardState move = BoardState {
    lastMove = move
  , gameResult = Nothing
  , pieceMove = []
  , moves = [move] -- ^ accept empty positions, filter when creating pgn
  , _position = Macbeth.Fics.Api.Move.position move
  , preMoves = []
  , perspective = if relation move == Observing then White else colorUser move
  , mousePt = Point 0 0
  , promotion = Queen
  , draggedPiece = Nothing
  , isWaiting = relation move == MyMove
  , psize = 40
  , scale = 1.0
  , pieceSet = head pieceSets
  , phW = []
  , phB = []}